1. Field of the Invention
The present invention relates to organic glass polymers for use in optical lenses and the lenses prepared therefrom. More particularly, the present invention relates to the excellent polymers for use in optical lenses having a high refractive index and the lenses prepared therefrom.
2. Description of the Prior Art
In recent years plastic lenses have come into wide use and in many cases have replaced inorganic glass lenses.
Plastic lenses have many advantages which inorganic glass lenses do not, namely low weight, impact and shatter resistance, easier processability and good dyeability, among others. In these days, polymethylmethacrylate, polydiethyleneglycol bisallylcarbonate, polycarbonate, polystyrene and the like have been widely used in various fields.
Especially in the field of ophthalmic lenses, low weight, high impact resistance and stiffness are strongly desired. Unfortunately, polydiethyleneglycol bisallycarbonate, the predominantly used material in making plastic ophthalmic lenses, has a relatively low refractive index (.eta..sub.D) of 1.50. This means that the lenses composed of polydiethyleneglycol bisallycarbonate are significantly thicker than comparable inorganic glass lenses.
While polycarbonate and polystyrene have relatively high refractive indices they are unsuitable for ophthalmic lenses because of their low heat resistance, poor solvent resistance and low Abbe number.
Thus, there has been a strong need for a plastic material having good optical properties including a high refractive index and a high Abbe number for use in ophthalmic lenses.
It has now been found that an organic glass having a high refractive index, excellent heat and impact resistance, and other desirable properties for lenses can be obtained by polymerizing a specific unsaturated urethane compound as a main component.